The invention relates to an HMI device. In particular, the invention relates to an HMI device equipped with an optical touch screen.
Technical installations are often controlled and operated with the aid of digital programmable data processing systems. The term ‘technical installation’, as used here, designates any type of technical equipment and systems arranged either individually or in a data network, e.g., via a field bus. Technical installations in an industrial application should be understood to mean, inter alia, items of individual equipment, such as drives, machine tools, intelligent transducers, sensors, etc. A technical installation, however, can also be an entire production plant in which an entire technical process is operated with locally distributed equipment, e.g., a chemical plant, an assembly line or a processing plant.
Technical installations are operated and controlled with the aid of digital programmable data processing systems, which often take the form of an automation system or a component thereof. Automation systems are equipped with special devices that form the interface between an operator and the automation system. Such devices are generally referred to as HMI devices, i.e., “Human Machine Interfaces.” This line of equipment is also referred to as devices for the “control and monitoring” of technical installations or “C&M devices” for short. These devices are connected upstream of the devices that are used for the direct control of a technical installation, e.g., the PLCs or Programmable Logic Controllers. This relieves a central control device, e.g., a stored program controller or SPC.
The term HMI equipment or HMI device should be understood as a generic term and also includes all the components belonging to this group. Examples of such components are, e.g., operator panels or OPs for short and industrial personal computers or IPCs used as HMI devices or associated programming devices. HMI devices, due to their special functionality, may assume functions, e.g., in a networked automation system, which can be generally viewed as specifying and post-processing data of the technical installation to be controlled. This function is also generally referred to as supervisory control and data acquisition (SCADA). For this purpose, an HMI device must typically execute a special type of software. Thus, an HMI device provides functions enhancing the comfort, quality and safety of an operator's control, e.g., an overview of the equipment to be operated and error-free operator actions.
HMI devices can be used, for example, not only to visualize and control interactive process images of the technical installation to be controlled but also to configure and generate them. This makes it possible, on the one hand, to selectively display the responses of the technical installation, typically in the form of measured values and signals. On the other hand, by specifically defining operator actions, the technical installation can be brought into desired states. In addition to these “monitoring and control” functions, an HMI device can be used for plant-specific configurations, e.g., to configure interactive process images.
The housings of prior art HMI devices are structurally designed in such a way that they can be installed as flush as possible in flat surfaces located, for example, on the outside of switchgear cabinets, on the topside of industrial control panels, operator consoles, control cabinets, etc. One housing side of the HMI device is configured as a user panel that lies as flush as possible on the respective surface, e.g., the door of a switchgear cabinet. The contact surface may be built in such a way that the entire arrangement meets the required degree of protection against dust and moisture, e.g., meets the IP65 or NEMY4x standard. The electrical and electronic components of the HMI device are accommodated behind the user panel in a box-like attachment whose dimensions are smaller than the length of the edges of the user panel. When such an HMI device is installed, e.g., in the surface of a control console, the box-like attachment can therefore be lowered into a corresponding recess while the protruding user panel sits on the edges of the recess and covers them completely. The user panel is normally sealed completely against external influences, particularly splash water and dust, and has electronic display elements, e.g., LCDs and keys or keypads. The keys or keypads can be configured, for example, as membrane keyboards with an application-specific arrangement and labeling. Such keypads can furthermore be largely sealed against external influences. In other embodiments, the HMI device can also be equipped with a touch display on the user panel. This touch display makes it possible to actuate switching functions by touching preprogrammed areas, e.g., in a process image configured for a specific application. In such an embodiment, additional keys or keypads can usually be eliminated.
HMI devices in the above-described widely used, and by now practically standard, conventional packaging structures have various drawbacks. For example, HMI devices with separate keypads are limited in the extent to which they can be adapted. Although the existing keys of such an HMI device may be assigned different functions, the number of the keys and their layout can of course no longer be changed. In contrast, for example, keypads displayed on HMI devices using a touch display can be adapted as a function of the application to reflect practically any modifications in the associated technical process. The use of a touch screen in an HMI device, however, is technically complex. Furthermore, the use of HMI devices with a touch screen, especially in a harsh and dirty environment, may be problematic.